The present invention is directed to apparatus adapted to be mounted on one or more driven wheels of a motor vehicle in order to increase traction. More particularly, the present invention comprises a removable traction device which can be used to assist in extricating an automobile, truck or other vehicle from mud, ice or snow. The traction device is adapted to fit a variety of tire sizes, can be conveniently stored in a motor vehicle until needed, and can be mounted and dismounted on a wheel without the use of tools.
The prior art is replete with apparatus intended to overcome the loss of traction due to the effects of ice and snow. Many such devices are prophylactic in nature, e.g., special tires or equipment designed to prevent the vehicle from becoming stuck. A common example of such apparatus are automotive, anti-skid tire chains, which are designed to be mounted on the drive wheels of a motor vehicle at the onset of winter and to remain upon the vehicle for an extended period of time. Not only are tire chains difficult to install and remove, but they are also generally necessary for only a few winter days in many locales.
Other examples of traction devices designed to be mounted on a vehicle wheel prior to venturing into ice and snow are found in the following prior art patents, viz., U.S. Pat. No. 2,722,260, and U.S. Pat. No. 4,244,412. A common deficiency with such devices is that they are typically quite difficult to attach to a vehicle wheel after the car has become stuck or mired.
The prior art contains several devices which, like the apparatus of the present invention, are designed to be mounted on a pneumatic tire of a mired auto or other vehicle to extricate the vehicle from ice, snow or mud. A feature common to all of these prior art devices is that they must be fairly precisely engineered to fit the size and contour of the tire with which they are utilized. In view of the variety of tire sizes in use today, manufacture and inventory of a number of sizes required to fit all vehicles is a difficult proposition. Moreover, the cross-section (profile) of a tire is highly dependent on the degree of inflation, which in turn is temperature related. As a result, a device designed to fit snuggly around a tire which is properly inflated might very well be inappropriate to the same tire in an under-inflated condition.
U.S. Pat. No. 2,518,170 discloses a traction device for a pneumatic tire comprising a pair of clamp members pivotally joined at the road-bearing surface. The device illustrated in this patent must be carefully fitted to the tire since the device is adapted to be mounted on the vehicle's tire rim. In addition, the patent teaches that a tool is required to mount or dismount the device from the tire.
U.S. Pat. No. 4,244,412 shows an anti-skid device formed of a plurality of inter-connected U-shaped elements. Like the apparatus of the present invention, the apparatus illustrated in this patent employs an upwardly curving segment on the base of the U-shaped device to transmit locking forces to the vertical sections of the traction device in order to more closely grip the sidewall of the tire on which it is mounted. This patent teaches the necessity of a supplemental apparatus to secure the device to the tire rim. Moreover, the device illustrated in the patent closely follows the contour of the tire sidewall.
U.S. Pat. No. 2,625,193 depicts a multi-element wire loop device adapted to be mounted on a pneumatic tire. Like the U.S. Pat. No. 4,244,412 patent, this patent teaches the desirability of utilizing an upwardly curving surface of the traction device to provide better gripping action. Additionally, the patent teaches the use of protuberances along portions of the contacting surface of the traction device to retain the device on the tire. The device illustrated in this patent is designed to closely mirror the geometry of the tire on which it is mounted.
U.S. Pat. No. 3,323,572 shows an anti-skid device which utilizes an adhesive backing for mounting the device to a tire. Although this apparatus can be employed with a variety of tire sizes, the apparatus is suitable for one-time use only, unlike the device of the present invention which can be easily dismounted and stored for re-use.